I'm a Linux user and will be the first to admit there is no "OS war". Microsoft has a virtual monopoly. The invisible hand of the market is fisting the world with the IE logo tattooed right on the middle finger.
Seconded, mostly because it turns out to be like this: "So you want a computer, huh? Well, if you're artsy and have lots of money to spend on pointless proprietary hardware, get a Mac. Otherwise, get a Windows machine. And don't get Linux unless you already know Linux."
Really, what gave Microsoft the virtual monopoly in the first place is that it's (comparatively) cheap since you don't need specialized hardware and their Windows is generally user-friendly. To my knowledge, what originally got them in trouble was that they were bundling their Internet Explorer with their OS and it's not like there were any good alternatives for Windows at the time anyway.